Activating KIRs on Educated NK Cells Support Downregulation of CD226 and Inefficient Tumor Immunosurveillance

Abstract

Therapies using NK cells (NKc) expanded/activated ex vivo or stimulated in vivo with new immunostimulatory agents offer alternative opportunities for patients with recurrent/ refractory tumors, but relevant biomarkers to guide the selection of patients are required for optimum results. Overall survival of 249 solid cancer patients was evaluated in relation to the genetics and/or the expression on peripheral blood NKcs of inhibitory and activating killer-cell immunoglobulin-like receptors (iKIR and aKIR, respectively), HLA class I ligands, CD226 (also known as DNAM-1), and NKG2A. Compared with patients with higher expression, patients with low expression of CD226 on total NKcs showed shorter mean overall survival (60.7 vs. 98.0 months, P < 0.001), which was further reduced in presence of telomeric aKIRs (KIR2DS1-DS5 and/or KIR3DS1, 31.6 vs. 96.8 months, P < 0.001). KIR2DL2/S2 þ , KIR3DL1 þ , KIR2DL1 þ , and KIR2DL3 þ NKc subsets in the presence of their cognate ligands primarily contributed to shortening patients' overall survival by increasing the sensitivity to CD226 downmodulation in aKIR-rich telomeric genotypes. In patients with high tumor burden who died during the follow-up period, aKIR-rich telomeric genotypes were associated with: (i) specific downmodulation of CD226 on educated NKcs but not on CD8 þ T cells or uneducated NKcs, (ii) lower expression of CD226 and higher expression of NKG2A on aKIR þ NKcs, and (iii) lower numbers of total CD56 dim NKcs. The reduced expression of CD226 on NKcs with aKIR-rich genotypes may be a biomarker indicative of NKc hyporesponsiveness in patients that could benefit from new NKc immune-stimulatory therapies.

KIR+ CD8+ T Lymphocytes in Cancer Immunosurveillance and Patient Survival: Gene Expression Profiling

“…In fact, higher frequency of aKIRs or Bx centromeric and telomeric genotypes has been associated with gastric cancer, non-Hodgkin lymphoma, and childhood acute lymphoblastic leukemia. However, these results contradict those reporting survival benefits for patients with acute myeloid leukemia (AML) who have received grafts from unrelated donors with 1 or 2 KIR B-haplotypes (recently reviewed by Guillamón et al [ 18 ]). Although, aKIRs and NKG2D share DNAX activating proteins (DAP10 and DAP12) in the signaling pathwaysof T and NK cytotoxic cells [ 19 ], NKG2D signaling determines distinct functional outcomes: direct activation of cytotoxicity and cytokine production in NK cells, but co-stimulation in activated CD8+ T cells only, so that T cells will require additional signals, especially from the T cell receptor (TCR), to build up a complete functional response.…”

“…This prospective observational study included 42 healthy Caucasian volunteers (control group) and 249 consecutive Caucasian patients with melanoma ( n = 80), bladder ( n = 80), or ovarian ( n = 89) tumors ( Table 1 ). These series of controls and cancer patients coincide with the cohorts used in previous studies, whose aim were to assess the role of inhibitory and activating KIR receptors on NK cell education and tumor immune surveillance [ 18 , 20 ]. Peripheral blood samples anticoagulated with EDTA were obtained from controls and patients from the Clinic UniversityHospital Virgen de la Arrixaca and General University Hospital Santa Lucía (Murcia, Spain).…”

“…The expression of KIR receptors (KIR2DL1, 2DS1, 2DL2/S2, 2DL3 and 3DL1) on CD3+CD8+ T cells and CD3–CD56+ NK cells in peripheral blood was evaluated as a percentage of positive cells using LSR-II and DIVA Software (BD, San Diego, CA, USA), as previously described [ 18 , 20 ]. LSR-II photomultiplier (PMT) voltages were adjusted daily using rainbow calibration particles (BioLegend, San Diego, CA, USA).…”

“…HLA-A, -B, -C and KIR genotyping was performed in DNA samples extracted by QIAmp DNA Blood Mini kit (QIAgen, GmbH, Hilden, Germany) using sequence-specific oligonucleotide PCR (PCR-SSO) and Luminex ® technology with Lifecodes HLA-SSO and KIR-SSO typing procedure (Immucor Transplant Diagnostic, Inc. Stamford, CT, USA), as previously described [ 18 , 20 ]. HLA-C genotyping allowed distinction between HLA-C Asn80 (group-C1) and HLA-C Lys80 (group-C2) alleles [ 51 ].…”

NK Cells in the Treatment of Hematological Malignancies

“…Significantly, allogeneic NK cells preferentially kill poor prognosis leukemia cells ( TP53 mutated) that are resistant to classical chemotherapeutic drugs [56]. Furthermore, the immunosuppressive profile of NK cells frequently observed in advanced cancers may significantly reduce the efficacy of HSCT [57,58] and other NK cell-based therapies [59,60]. Impaired NK cell-cytotoxicity also interferes with the response to chemotherapy with azacitidine (AZA) and reduces the survival of patients with AML [61], suggesting that NK cell function may also play a significant role in the response to more conventional chemotherapeutic agents.…”